Hydrocarbon isomerization process and catalyst treatment



June 28, 1960 HYDROCARBON ISOMERIZATION PROCESS AND CATALYST TREATMENT SELECTIVITY WATER CONTENT OF CATALYST, WT.

N. L. CARR Filed Nov. 5, 1957 WATER PARTIAL PRESSURE mm Hg abs.

ATTORNEY I NVE NTOR EFFECTIVE RANGE FOR WATER TREATMEN 0.4

FIG. I

0 WATER PARTIAL PRESSURE. mm H 5 lb 50 I00 o o &

0 8 EFFECT OF WATER m o HYDROGEN TREATMENT 90 0 8 ON SELEOTIVITY- M F I 60 nor HIGH ACTIVITY u LOW ACTIVITY AND INOPERABLE M o IIO 20 so 40 ms United States Patent I H I 2,943,127 7 HYDROCARBON ISAOMERIIZATION PROCESS AND CATALYSTTREATMENI Norman L. Carr, Crystal Lake, 111., assiguorto The Pure Oil Company, Chicago, 111., a corporation of Ohio Filed Nov. 5, 1957, Ser. N... 694,586

13 Claims. ((31. 260-68365) t This invention relates to the catalytic hydroisomerization of isomerizable, C -C hydrocarbons. It is more 2,943,127 Patented June 28, 1960 ice '- ployed in the process of this invention for specific specifically directed to the upgrading of low-octane-number hydrocarbon feed stocks derived from crude petroleum oils.

In the processing of crude petroleum oils for the manufacture of high-octane gasolines, a variety of unit processes are employed in treating the distillate stocks to provide blending stocks which may be employed in the formulation of a finished gasoline-type motor fuel. The major constituent of a gasoline pool is the gasoline derived from the catalytic cracking of gas oils obtained from the distillation of the petroleum oil. schemes involving polymerization and alkylation are available 'for processing the available, normally gaseous, feed stocks. Generally, the C virgin gasolines are catalytically hydroformed to cyclize and aromatizethe Various constituents of the ,feed stock which'response to this type of treatment. Although isomerization is one of the concomitant reactions in the hydroforming' process, this is a competing equilibrium-type reaction; Accordingly, maximum efiiciency is not obtained with respect to this particular reaction. Furthermore the hydrofonning type of refining processes yields gasoline blending stocks which have a high research octane number, but they have high sensitivity because the improvement in motor octane value and research octane value is not effected at the same rate. Fuels which are suitable for use in high-speed, high-' output, spark-ignited internal combustion engines preferably have a relatively low sensitivity. One particular technique for reducing fuel sensitivity is'to incorporate in the finished gasoline isomerized, straight-run components. Accordingly, it is desirable to employ an isomerization process in a refining scheme for the, production of a finished, high-octane-number gasoline having low sensitivity; In general, the isomerizable feed stock is taken from a 0 virgin gasoline stock and constitutes a straight-run or natural gasoline feed stock, having an ASTM boilingrange of from about 90 F. to about 210 F., containing substantial amounts of isomerizable, straight-chain-paraffinic hydrocarbons. I

I Ajnumber of liquid-phase isomerization processes employa Friedel-Crafts-type catalyst, and vapor-phase isom- .erization processes using solid' catalyst have been developed. The efficiency of these processes is considerably influenced by the type of-catalyst employed. 7 7

Therefore, it is the primary object of this invention to provide a non-corrosive, highly selective, solid catalyst for the conversion of normal pentane, normal hexane and normal heptane or mixtures thereof to high-octane-number, branch-chain isomers at a high yield. Another object of this invention is to prepare an isomerization catalyst which is employed in the hydroisomerization of suitable isomerizable feed stocks at a temperature of about 600-750 F., a pressure of from about 180 to 1000'p.s.i., and a, hydrogen/hydrocarbon molratio of about 0.5 to 415." It is another 'objectof this invention to provide a hydr i zat g ses .isr. t ad n of 1 SiO -Al O catalyst compositions prepared by incorporating the promoter in the -green catalyst as NiMoO and subsequently activating.

Investigators of the isomerization process catalyzed by a solid type of catalyst have found that a catalyst composite prepared by incorporating small amounts of a hydrogenation agent on an acidic oxide catalyst support,

said support composited to evince acidic properties and, I

can be employed in the preparation of such catalysts are the known hydrocarbon cracking catalysts. These in clude butare not limited to silica-alumina, silica-zirconia, silica-titania, silica-boria, alumina-zirconia, aluminaberyllia, alumina-boria, silica-chromia, boria-titania, silica alumina zirconia, silica-alumina-beryllia, acidtr'eated clays, .etc The oxides employed in forming the base can be either. in chemical 'or physical combination. It'h'as-been found according to this invention that selected promoters, when incorporated in the acidic oxide catalyst base, are receptive to a catalyst treatment technique which enhances the hydroisomerization efficiency of the composite catalyst. 'Heat-stable'promoters which are used in the preparationot promoted, acidic oxide, hydroisomerization catalysts include group VIIImetals' of the iron series; group VIII metal of the iron series salts of the oxy-acids of tungsten, and molybdenum; and the oxides of molybdenum and tungsten. For example, iron,

nickel, or cobalt; iron, nickel, or cobalt molybdate or;

tungst'ate; or molybdenum or tungsten oxide. s

.In the preparation of catalysts of this nature, the composite is activated in the final'step of the catalyst prepara: tion in the presence of hydrogen, or subjected to a: hydro gen treatment-prior to use, in order'to reduce the re-. ducible metal ions in'the catalyst compositionto substantially the lowest state of valency under the conditions of reduction. A variety of methods have been devised and are described in the prior art for preparing these catalysts. For example, catalyst comprising silica-alumina and group VIII metals can be prepared impregnating the silicaalumina carrier with a solution of a soluble group VIII metal salt, such as the acetate, nitrate,- or complex group VIII metal ammonium compound, or the molten salt may j be employed in, impregnating the 'silica-alumina The;

group VIII metal. is then produced by decomposing and reducing the compound with a reducing gas, such as hy drogen. 'Another technique involves the mixing of a solu tion of a group'VIII metal salt with the silica-alumina carrier. A group VIII metal hydroxide or carbonate is y decomposition and'reduction of 1 carbonate. In certain instances'it maybe preferred to heat the impregnated group VIII metalcoinpound'in-ja I suitable oxidizing atmosphere prior to reduction to the r 8 metal- A more'recent technique the;

3 preparation of a silica-alumina carrier having incorporated therein a highly active, finely divided catalyst involves impregnating silica-alumina with solution of a complex group VIII metal ammonium salt, and thereafter contacting the impregnated silica-alumina with carbon dioxide to produce the carbonate. The impregnated carrier is then dried and calcined at a temperature at which the carbonate will decompose to form the oxide, after which the oxide is subjected to reduction to form the metallic catalyst. It is essential in preparing catalysts of this nature, wherein an ammonium compound is employed in the catalyst preparation, that reducing condi tions of time and temperatures suflicient to effect the substantially complete removal of ammonium ions from the catalyst be utilized in order to avoid adversely afiecting catalyst activity. In the event that group VIII metal of the iron series salts of oxyacids of molybdenum, or tungsten, or the oxides of molybdenum or tungsten are employed in preparing the composite catalyst, the catalysts are treated at elevated temperatures with a suitable free hydrogen-containing or -producing agent in order to reduce the reducible metal ions to substantially the lowest valency state obtainable at the reducing conditions employed.

The mixed oxide support can be prepared by separately mixing prepared proportions of refractory oxides which, when composited, will evince the necessary acidic characteristics and also have hydrocarbon cracking activity. In addition, these catalyst constituents can be prepared by conventional coprecipitation techniques. In other words, in preparing the acidic oxides-hydrogenation agent composite for usein carrying out the instant invention, any conventional catalyst synthesis can be utilized wherein the finishing step involves exposing the catalyst composi tion to a hydrogen atmosphere in order to eflect the reduction of the reducible constituents of the catalyst'composition to the lowest state of valency obtainable at the conditions of reduction.

It is known that special catalyst conditioning procedures are frequently employed in order to insure maximum catalytic activity. In accordance with this invention, it has been found that the promoted, acidic oxide composite, hydroisomerization catalysts employed in this invention can be improved with regard to yield, selectivity and stability by incorporating in a hydrogen-rich, treating-gas stream, employed in the ultimate step in the catalyst preparation and/or treatment, a partial pressure of water vapor and contacting the catalyst at an elevated temperature for a time suflicient to permit the interaction of water and the catalyst to reach equilibrium at the. treating conditions employed. The partial pressureof: the water vapor in the oxidizing and/or reducing gaseous stream depends upon the temperature at which the water equilibration is carried out. The selectivity is improved by treatment with water vapor at temperatures of not less than about 700 F.; however, the desirable range of partial pressure of water vapor is shifted to lower values as temperature is lowered. .The role of the interaction between the catalyst and the watervapor, which produces the improved selectivity, decreases somewhat as the temperature is lowered to the 700 F. level. Consequently, although temperatures as low as about 700 'F. can be used, if the rates at which equilibrium is reached are too slow, the water-equilibration is impractical and uneconomic.

In carrying out the catalyst treatment technique which is the subject matter of this invention, in one embodiment, a green catalyst is prepared in any suitable man ner, such as outlined above. Thereafter the greencatalyst is activated by employing a conventional, oxidation-reduction cycle, or a simple reduction. In order to efiectuate the objectives of this invention, the reducing gases which. are utilized in this activation step are humidified in order to incorporate a suitable amount of water vapor in the gaseous treating stream.

To efiect the evaporation of water into the processing gases, viz., reducing gaseous streams, for the purpose of humidifying the gases, conventional techniques can be used. To add suflicient amounts of water to provide the desired partial pressure, the humidity of the gas stream can be employed as the criterion if desired because this property is related to the partial pressure of the water being carried. If

p=partial pressure (absolute units),

Pztotal pressure of the gas-water mixture (absolute units),

Mw=molecular weight of the water=18, and

Mg=molecular weight of the gas, then is y In addition, water partial pressure can also be calculatedfrom the wet-bulb depression of the processing gas resulting from its humidification or dehumidification (see Unit Operations, Brown et al., Wiley, 1950, chap. 37). Humidification of the processing gases preferably is carried out using an indirect system in which the water is sprayed into the processing gas before it contacts the catalysts being water-equilibrated. To determine the proper humidity conditions, although the processing streams employed will not be air, results within the range of engineering accuracy will be obtained employing proper units on humidity charts for air-water systems. Of course, if the pychrometric properties of the processing gas sy tem actually to be employed are available, these should be used.

In carrying out the instant invention, although other humidification procedures can be used, it is preferred that an indirect humidification system be employed, such as a packed tower wherein water and the processing gas are countercurrently contacted, under conditions such that the gas is saturated with water at the selected conditions of temperature and pressure. At dynamic equilibrium conditions, the vapor pressure of the water will be equal to the partial pressure of water in the processing-gas efiluent from the humidifier. Although this assumes ideal gas conditions, analysis of the efliuent processing gas corroborates the accuracy of this technique. In general, the humidification will be carried out at pressures within the range of 0 to p.s.i.g-. and at a temperature selected to effect the Humidity (lb. Water/lb. dry gas) desired humidification, generally within the range of about 50 to F.

The humidified processing gas is then heated to the selected processing temperature and the catalyst composition treated until not only the desired functional etfect of the processing step, viz., reduction of the reducible constituents of the catalyst composition is effected, but water equilibration of the catalyst composition by the humidified processing stream is accomplished. This latter condition is indicated by the absence of any substantial difference between the water partial pressure in the processing gas introduced into the catalyst bed' and .the efiiuent removed.

Because controlled humidification of theactivation gases is an important aspect of the instant invention, it is necessarythat the concentration of water in the activation streams be controlled within narrow ranges depending upon the activation temperature. Reference is made to Fig. l which shows a graphical presentation of' various temperatures which can be employed in activating the proinoted acidic oxide composite hydroisomerization catalyst employed in this invention. It will be noted that a circumscribed area is provided on this graphical presentation. According to this invention, control of the partial pressure of water. in the freehydrogen-containing, treating gasesmustbe. maintained within this area and correlated with. a selected treating temperature to obtain maximum efiici'ency;

To illustrate the efiectiveness of the instant invention;

vsults from the virgin or untreated catalyst.

a catalyst, a nickel, molybdenum oxide, silica-alumina catalyst composite, was prepared as follows:

An ammoniacal solution of para-molybdate was prepared by dissolving 32 grams of ammonium heptamolybdate (NHUBMO'TOMAHEO in 270 ml. of distilled water to a salt content of about 11% by weight. To this solution was added 20 ccgof concentrated ammonium hydroxide to provide an ratio of about 0.075/1. An 18 weight percent solution of nickel nitrate was prepared by dissolving 58.7 grams of Component: Wt. percent A1 23.13 Na O 0.02 Fe 0.02 80., 0.25 SiO 76.59

aerate? i The resulting slurry was mixed for one hour at 176 F., and then was filtered, washed with water, pelleted to provide A" pellets, and dried for 16 hours in an oven at 230 F. to provide a green composite containing 10% NiMoO, on the silica-alumina support.

To activate the catalyst, employing a conventional catalyst preparation, 170 ml. of green catalyst A was inserted in a reactor and heated rapidly to 400 F. with 10 s.c.f.h. of hydrogen flowing through the reactor. The temperature of the catalyst was raised, at a rate of 100 F. per hour, to 975 F. employing a hydrogen rate of 10 s.c.f.h. This hydrogen rate and temperature was maintained for one hour after which the hydrogen rate was reduced to 4 s.c.f.h. and held for 6 hours at 975 until no ammonia was detected in the off gas. The catalyst was then cooled to run temperature and employed in the npentane isomerization run defined in Table 1.

Another batch of 150 ml. of green" catalyst (B),

similarly prepared, was disposed in a reactor. This catalyst was decomposed as was catalyst A, except that the time at 975 F. was 29 hours. The temperatnr e'then was lowered to 825 F. at which level the catalyst was equilibrated with hydrogen containing moisture, at a level of 22 mm. (mercury) partial pressure, for 50 hours. The conditions were then changed to those of the defined run. The result is noted under column heading (1) in Table 1. Another example with the same catalyst, but treated at difierent conditions with moisture in the hydrogen, is given under heading (2), Table I.

' These catalysts were disposed in a'reactor under suitable reaction conditions, and a feed stock consisting essentially of normal pentane was introduced into the reaction system and processed under isomerization conditions. As mentioned, the results of these runs are tabulated in Table I. The effectiveness of the instant invention is readily seen when the conversion, yield, and selectivity results for the preconditioned catalysts are comparedwith the re- In addition to lower yield results, catalyst A produced excessive hydrocracking.

The effect of employing water partial pressures outside the critical range is illustrated by Figure 2.

Although the advantages which are obtained by the o. no. '3. October 17, 1955, at page 121, et seq.

TABLE 1 Processing conditions Temperature, F- 700 Pressure, p.s.i.g- 500 Hg/H-Qs 11101 I'Mlfi 1. 0 LVHSV a. a

. A Water Equilibrated,

, Catalyst "13 Oonventlonally Prepared Catalyst 11' n-Pentane conversion I 51 41. 0 41. 7 i-Pentane yield 35 37. 8 39. 2 Selectivity 68 92. 3 93. 9

Reaction Efi-luent, Wt. Percent Charge:

Methane 0. 68 0. 52 Ethane 0. 12 0. 29 Propane O. 30 0. 55 Butane 1. 83 1. 28 Isopentane 35. 6 38. 73 40. 05 n-Pentane 46. 9 55. 96 55. 23 Oyclopentane +hexane 1. 6 2. 3 2.13

isothermal reactor; it would 'be impossible to operate adiabatically.

This is because of the high exotherm nature of the hydrocracking re- 011.

instant invention are illustrated by the data in Table I, which are with a virgin catalyst of high activity and selectivity, the instant invention also has application in the hydrogen treatment of a regenerated, spent catalyst ,to provide a revivified catalyst having a high selectivity and activity. This phase of the instant invention is carried out as a supplementary step in a conventional oxidationreduction cycle, regeneration process wherein a spent, promoted, acidic oxide, hydroisomerization catalyst is oxidized at a temperature within the range of about 850 to 950 F. In the oxidizing step a suitable, free-oxygen containing gas, e.g., air, is employed. If desired, the temperature of the catalyst bed, after the burning has ceased, can be raised to not higher than about 950- 1000" F. This high temperature is to be initially avoided during the oxidation step because the'resulting sintering' causes a substantial reduction in activity and surface area. The oxidized catalyst is thereafter reduced at a temperature of about 9501000 F. in the presence of a free-hydrogen-containing gas. In this step the hydrogen-containing gas in introduced at a suitable rate for about 10 to 30 hours to effect the reduction of the rel ducible constituents of this catalyst.

If the water-equilibration aspects of this invention are employed in the preconditioning of a catalyst composition which has been previously activated by treatment with a free-hydrogen-containing reducing gas, another important factor which affects the level of activity is the water' content of the hydrogen employed in this reducing step prior to water-equilibration. This condition has been termed catalyst dryness, and is defined as the moisture level in the hydrogen employed in the reductionphase of the activation or regeneration at catalyst conditions I effect the concomitant reduction of the reducible constituents of the catalyst and the desired equilibration. In.

Table II are shown data which illustrate that the catalyst dryness plays an important part in activity, and that the catalyst should be treated with dry hydrogen in the reduction phase of the activation or regeneration cycle for best results.

It is also desirable in employing the process of this'invention in conjunction with the regeneration of the se-' lected, promoted, acidic oxide,hydroisomerizationcati alyst employed in this invention to avoid the useof an f intermediate, vacuum-purging step in the oxidationdonate generation cycle because this step can lead to substantial decrease in activity when there is considerable sulfur added to the catalyst during processing.

It is also preferred to utilize a two-level temperature treatment in the water-equilibration treatment of this invenion. The higher temperature is generally within the range of 925 to 975 F., and the lower temperature is a temperature above the temperature used in the hydroisomerization process, viz., 700-850 F., but about 75 to 275 F. lower than the initial temperature. It has been found, for example, that two-level treatments employing temperatures of 975 and 800 F., and 975 and 700 F., respectively, provide an increase of 3.5 selectivity units with a concomitant butane production rate of one-half as compared with a one-level temperature treatment at the lower temperature.

Although the foregoing illustrative embodiments of this invention utilize a nickel-containing promoter incorporated in a silica-alumina hydrocarbon cracking catalyst base,

it is to be understood that the instant invention is broadly directed'to decreasing hydrocracking reaction rates by the water-equilibration of composite catalysts consisting essentially of a major portion of a refractory acidic oxide catalyst, composited to evince hydrocarbon cracking activity and acidic properties, and a minor portion of a promoter selected from the group consisting of group VIII metals of the iron series, e.g., NiSiO Al O group VIII metal of the iron series salts of an oxyacid of tungsten or molybdenum, e.g., nickel molybdate-silicaalumina and nickel-tungstate-silica-zirconia; and the X- ides of molybdenum or tungsten, e.g., tungsten oxidesilica-alumina, molybdenum oxide-silica-zirconia, especally for use in the isomerization of C -C isomerizable hydrocarbons. In the promoter, the metal ions exist in substantially their lowest state of valency attainable at the reducing conditions utilized in the catalyst preparation.

The catalyst composition will consist essentially of the acidic oxide catalyst support having incorporated therein 0.5 to 8% by weight of a single, selected promoter. To facilitate a determination of the amount of promoter to be employed, and because of the inability to define the promoter constituents in their reduced state with precision, it is preferred that these amounts be based upon the proportion of promoter incorporated in the catalyst composite prior to activation, whereby the valency state of the reducible ions in the promoter may have been lowered, and/ or the catalyst water equilibrated. Preferred supports are the silica-alumina hydrocarbon cracking catalysts having silica contents within the range of about 50-95 wt. percent; however, other acidic oxides compositions can be used. Preferred promoters used to initially prepare the catalyst, and which are subjected to further treatment to effect their reduction, arenickel-containing materials, for example, metallic nickel, nickel molybda'te, other combinations of nickel and molybdenum oxides, and similar materials. As discussed above, the water-equilibration is carried out by incorporating a small amount of water in the hydrogen treating agent employed in the conditioning step. The water is added to the reducing gases in small amounts depending upon treating temperature. The following represents in tabularform a summary of the partial pressure condition that should exist within the gas streams employed in the preconditioning step.

Lower U per Limit Limit The water equilibration step of this invention has application in improving the activity and selectivity of the above-mentioned promoted acidic oxides in a variety of catalyst preparations and techniques. In general, the water equilibration is the final step in the catalyst treatment wherein a humidified, free-hydrogenrich gas having a water partial pressure, depending upon the treating temperature, within the range of 5-100 mm. of mercury absolute, and preferably 10-30 mm., is employed to elfect the desired improvement in catalyst properties. The humidified hydrogen is introduced at arate and for a time sufficient to bring the catalyst composition being treated into equilibrium with the treating gas, and, depending upon the state of the catalyst composition being treated, to effect the reduction of the reducible ions of the catalyst composition to the lowest state of valency attainable at the treating conditions. In general, the humidified hydrogen is introduced at a linear rate within the range of 10 to 100 'feet per minute for about 2-20 hours employing a temperature within the range of about 700-975 F.

Accordingly, the water-equilibration, catalyst treating step of this invention can be used as a concomitant activation and conditioning step in the activation of a green catalyst; as a supplementary hydrogen treatment in the conditioning of an active catalyst wherein the selected promoting agents are reduced and are at the lowest state of valency obtainable under the reduction conditions employed in the catalyst activation; in the enhancement in emciency of a regenerated, spent catalyst which has been revivified by means of a sequential oxidation-reduction cycle; or in various other catalyst preparations, which, in view of the foregoing discussion, will be apparent to those skilled in this art.

Although the instant invention has application as a unit process for the isomerization of suitable hydrocarbon feed stocks, it is advantageously employed in conjunction with a reforming or hydroforming operation wherein se' lected hydrocarbon feed stocks are transformed to highoctane-number gasoline-blending stocks. In carrying out the isomerization phase of this invention, the following operating conditions are employed.

It is preferred that this combination be employed in order to eifect substantial improvements in the yieldoctane number relationship of the product obtained by the processing of a full-boiling-range, virgin naphtha in an integrated, isomerization-reforming process.

Another important aspect of the instant invention is the use of the so-called split-stream treatment of feed stocks in order to more advantageously process the respective constituents of the feed stocks. In other words, in employing the instant invention to effect maximum efficiency in the processing of a feed stock containing an admixture consisting predominantly of normal pentane, normal hexane, and normal heptane, it is preferred that each constituent be separately treated in reaction'systems' designed and operated under conditions especially adaptawen-mi, J

ble for obtaining effectiveness. .Reaction systems may be designed for treating a combination n-C -n-C stream and a Ill-C7 stream, the processing of each of the principal constituents separately, or the processing of a n-C stream and the processing of a combination normal hexane, normal heptane stream. This, of course, requires prefractionation of the feed stock in order to provide satisfactory feed streams.

The instant invention is directed to the improvement of isomerization catalysts for use in the processing of n-C -C -containing feed stocks, either to effect their skeletal isomerization per se, or to prepare high-octanenumber blending stocks used in the formulation of motor fuels especially adapted to high-output, high-speed, sparkignitecl, internal combustion engines. Although the invention is illustrated with reference to specific catalyst compositions and specific operating conditions, it is obvious that modifications in the catalyst preparaton and isomerization other than those specifically set forth above can be made by those skilled in the art.

Accordingly it is intended that the instant invention be limited only in the manner defined in the followin claims.

I claim as my invention:

1. In a process for improving the selectively, yield and stability of a hydroisomerization catalyst composite consisting essentially of a major-portion of a refractory, acidic oxide catalyst support, containing 50-95% wt. silica, composited to evince acidic properties and hydrocarbon cracking activity, and .a minor amountof at least one promoter. selected from the group consisting of group VIII metals of the iron series, salts'of group VIII metals of the iron series and oxyacids; of molybdenum andtungstemand oxides of tungsten, and molybdenum, the ultimate step which comprises contacting said catalyst composite with a humidified, hydrogen-rich gas, having a partial pressure of water and a temperature within the shaded area of Fig. 1, for a time sufficient to permit the interaction between the water in said gas and the catalyst composite to reach equi ibrium at the contacting conditions employed.

2. In a process for improving and selectivity, yield and stability of a hydroisomerization catalyst composite consisting essentially of a major portion of a refractory, acidic oxide catalyst support, containing 50-95% wt. silica, composited to evince acidic properties and hydrocracking activity, and a minor amount of at least one promoter selected from the group consisting of group VIII metals of the iron series, salts of group VIII metals of the iron series and oxyacids of molybdenum, and tungsten, and oxides of tungsten and molybdenum, the ultimate step which comprises contacting said catalyst composite with a humidified, hydrogen-rich gas, having a partial pressure of Water and a temperature within the shaded area in Fig. l, for a time suflicient to permit the interaction between the water in said gas and the catalyst composite to reach equilibrium and to effect the reduction of the reducible metal ions of the promoter to their lowest state of valency under the hydrogen treatment conditions employed.

3. A process for improving the selectivity, yield and stability of a hydroisomerization catalyst composite consisting essentially of a major portion of a refractory, acidic oxide catalyst support, containing 50-95% wt. silica, composited to evince acidic properties and hydrocarbon cracking activity, and a minor amount or: at least one promoter selected from the group consisting of group VIII metals of the iron series, salts of group VIII metals of the iron series and oxyacids of molybdenum and tungsten, and oxides of tungsten and molybdenum, which comprises preparing a green catalsyt composite consisting of a composite of a major portion of said acidic oxide catalyst support and a small amount of said promoter, and thereafter activating and conditioning said catalyst by contacting said green catalyst with a hydrogen-rich reducing gas, having a water partial pressure and a temperature within the shaded area of Fig. 1, for

a time sufdcient to effect the reduction of the reducible metal ion constituents of the promoter to their lowest state of valency under the reducing conditions employed and to permit the interaction between the water insaid gas and the catalyst composite to reach equilibrium at the contacting conditions employed. I

4. In a process for improving the selectivity, yield and stability of an active hydroisomerization catalyst pre: pared by the hydrogen activation of a composite con.- sisting essentially of a major portion of a refractory, acidic oxide catalyst support, containing 50-95% wt. silica, composited to evince acidic properties and hydrocarbon cracking activity, and a minor amount of at least one promoter selected from the group consisting of group VIII metals of the iron series, salts of group VIII metals of the iron series and oxyacids of molybdenum and tungsten, and oxides of tungsten and molybdenum, the reducible metal ions of said promoter being at their lowest state of valency obtainable by said hydrogen activation, the ultimate step which comprises contacting said catalyst composite with a humidified, hydrogen-rich a refractoryfacidic oxidecatalyst support, containing;

50-95% wt. silica, composited to evince acidic properties and hydrocarbon cracking activity, and a minor amount of at least one promoter selected 'frorn the gruop consisting of group VIII metals of the ironseries, salts'of group VIII metals of the iron series and oxyacids 'of molybdenum and tungsten, and tungsten oxide and molybdenum oxide, said hydroisomerization catalyst having been regenerated by a sequential oxidation-reduction cycle, the ultimate step which comprises contacting said catalyst composite with a humidified, hydrogen-rich gas, having a partial pressure of water and a temperature within the shaded area in Fig. 1, for a time suificient to permit the interaction between the water in said gas and the catalyst composition to reach equilibrium at the contacting conditions employed. V

6. A process for improving the selectivity, yield and stability of a hydroisomerization catalyst composite consisting essentially of a major portion of a refractory, acidic oxide catalyst support, containing 50-95% wt. silica, composited to evince acidic properties and hydrocarbon cracking activity, and 0.5 to 8%, by weight, based on the amount initially incorporated in said composite, of a promoter selected from the group consisting of group VIII metals of the iron series, salts of group VIII metals of the iron series and oxyacids of molybdenum and tungsten, and oxides of tungsten and molybdenum, the ultimate step which comprises contacting said catalyst composite with a humidified, hydrogen-rich gas,

having a partial pressure of water and a temperature within the shaded 'area of Fig. 1, for a time sufiicient to permit the interaction between the water in said gas and the catalyst composition to reach equilibrium at the contacting conditions employed.

7. In a process in accordance with claim 6 in which said hydroisomerization catalyst is a nickel molybdatecarbon cracking activity, and a minor amount of at least. one promoter selected from the group consisting of group proving the selectivitypyield VIII metals of the iron series, salts of group VIII metals of the iron series salt and oxyacids of molybdenum and tungsten, and oxides of molybdenum and tungsten, the ultimate step which comprises contacting said catalyst composite with a humidified, hydrogen-rich gas, having a partial pressure ofwater within the shaded area of Fig. 1, for a time sufficient to permit the interaction between the water in said gas and the catalyst composite to reach equilibrium, at the contacting conditions employed said contacting being carried out at a first elevated temperature within the shaded area of Fig. 1 and thereafter completing said contacting at a second elevated temperature which is lower than said first elevated temperature but is not less than the reaction temperature employed in the hydroisomerization process utilizing said hydroisomerization catalysts.

- 9. A process in accordance with claim 8 in which said first elevated temperature is 975 F., and said second elevated temperature is within the range of 700-800 F.

10. in a process for improving the selectivity, yield, and stability of a "green hydroisomerizau'on catalyst composite, consisting essentially of a major portion of a 50-95% Wt. silica/50'-5% wt. alumina hydrocarbon cracking catalyst and a minor portion of a nickel molybdate, the ultimate step which comprises contacting said catalyst composite with a humidified hydrogen-rich gas, having a partial pressure of water of 22 mm. of Hg, for a time sufiicient to permit the interaction between the water and said gas and the catalyst composition to reach equilibrium, at the contacting conditions employed said contacting being carriedout initially at a temperature of 975 F. and thereafter at a temperature within the range of 700-800 'F.

11. A hydroisomerization process which comprises contacting an isomerizable hydrocarbon having -7 .carbon atoms per molecule in the presence of a hydroisomerization catalyst at a temperature within the range of 600-750 F., a pressure in the range of 180-1000 p.s.i.g.,

and a hydrogen/hydrocarbon mol ratio within the range of 0.5-4.5, said hydroisomerization catalyst having been prepared by a process including the step of ultimately contacting the catalyst consisting essentially of a major portion of a refractory, acidic oxide catalyst support, containing -95% wt. silica, composited to evince acidic properties and hydrocarbon cracking activity, and 'a' minor amount of at least one promoter selected from the group consisting of group VIII metals of the iron series, salts of group VIl I metals of the iron series salt and oxyacids of molybdenum and tungsten, and oxides of tungsten and molybdenum, with a hydrogen-rich gas containing water at a partial pressure and at a temperature within the shaded area in Fig. 1 for a time sufficient to permit the interaction between the water in said gas and the catalyst composition to reach equilibrium.

12. A process in accordance with claim 1 in which the isomerization catalyst comprises nickel molybdate supported on a 50-95% wt. silica/50-5% wt. alumina hydrocarbon cracking catalyst.

13. A process in accordance with claim 11 in which the isomerization catalyst comprises nickel molybdate supported on a 50-95% wt. silica/50t-5% wt. alumina hydrocarbon cracking catalyst.

References Cited in the file of this patent UNITED STATES PATENTS 2,292,570 Klemm et al Aug. 11, 1942 2,414,585 Eggertsen et a1 Jan. 21, 1947 2,424,636 Smith July 29, 1947 2,437,487 Teter Mar. 9, 1948 2,438,584 Stewart Mar. 30, 1948 2,718,535 McKinley et a1 Sept. 20, 1955 2,805,269 Carter et a1. Sept. 3, 1957 2,864,875 McKinley et a1. Dec. 16, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No; 2,943,127 June 28,. 1960 Norman L, Carr It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 32, for "response" read respond column 9 line 42, for "and" read the line 71 for "catalsyt" read catalyst column 10, line 35, for "gruop" read group Signed and sealed this 20th day of December 1960.

(SEAL) Attest:

KARL H. AXLINE Attesting Oflicer ROBERT C. WATSON Commissioner of Patents 

1. IN A PROCESS FOR IMPROVING THE SELECTIVELY, YIELD AND STABILITY OF A HYDROISOMERIZATION CATALYST COMPOSITE CONSISTING ESSENTIALLY OF A MAJOR PORTION OF A REFRACTORY, ACIDIC OXIDE CATALYST SUPPORT, CONTAINING 50-95% WT. SILICA, COMPOSITED TO EVINCE ACIDIC PROPERTIES AND HYDROCARBON CRACKING ACTIVITY, AND A MINOR AMOUNT OF AT LEAST ONE PROMOTER SELECTED FROM THE GROUP CONSISTING OF GROUP VIII METALS OF THE IRON SERIES, SALTS OF GROUP VIII METALS OF THE IRON SERIES AND OXYACIDS OF MOLYBDENUM AND TUNGSTEN, AND OXIDES OF TUNGSTEN AND MOLYBDENUM, THE ULTIMATE STEP WHICH COMPRISES CONTACTING SAID CATALYST COMPOSITE WITH A HUMIDIFIED, HYDROGEN-RICH GAS, HAVING A PARTIAL PRESSURE OF WATER AND A TEMPERATURE WITHIN THE SHADED AREA OF FIG. 1, FOR A TIME SUFFICIENT TO PERMIT THE 